Conjectures: True/False and Counterexamples.

EXAMPLE: All trees lose their leaves or needles in the fall.

ANSWER: The answer would be false because; pine trees do not lose thier needles in the fall

EXAMPLE: The sum of the sequence 1+2+2^2+...+2^n, where n is a whole number, is always a prime number.

choices are: a) when n=4, the sum is 31 b) when n=7, the sum is 57 c) when n=5, the sum is 63.. and d) there is no counterexample. The conjecture is true.
ANSWER: The answer would be [c] because 63 is not a prime number.